ObjectiveTo investigate the change in immunologic function of infants with Mycoplasma pneumonic pneumonia (MPP) in the acute and recovery phase, and compare with normal healthy children. MethodsPatient’s peripheral blood was withdrawn respectively when they admitted in hospital within 2 hours in the acute phase (before receiving treatment with antimicrobial agents),  having received macrolides for 2-4 weeks and when clinical and radiographic signs significantly improved ,then all specimens were detected.ResultsCompared with healthy infants and infants  in the recovery phase, the proportion of CD4 + T cells ,CTLA–4+T cells,CD4+ /CD8+, NK cells and the level of C3,C4 in patients with acute MPP were significantly lower (P<0.05)； the proportion of CD8+T cells,B cells and the levels of IgA,IgM,IgE were significantly higher (P<0.05). The proportion of CD3+T cells and the levels of IgG were not statistically different between two groups  (P>0.05).ConclusionThe immunologic function of patients are disordered in the acute phase of MPP, and still exist a certain degree of disorder during convalescence，immunological regulatory treatment should be given to infants with MPP , so as to reduce treatment course and improve  convalescence.